refactor(viewer): profile rerun loading by playback stage

apps/control-station/test/liveViewerDiagnostics.test.mjs

@@ -7,6 +7,7 @@ let createLiveViewerDiagnosticLifecycle;
 let createAbortFencedBuildVerifier;
 let createUiBuildStaleCoordinator;
 let liveViewerDiagnosticBody;
+let reloadRecordedViewerAfterStaleModuleFailure;
 let server;
 let uiBuildIdFromModuleScripts;
 let verifyLiveViewerClientBuild;
@@ -22,6 +23,7 @@ before(async () => {
     createLiveViewerDiagnosticLifecycle,
     createUiBuildStaleCoordinator,
     liveViewerDiagnosticBody,
+    reloadRecordedViewerAfterStaleModuleFailure,
     uiBuildIdFromModuleScripts,
     verifyLiveViewerClientBuild,
   } = await server.ssrLoadModule("/src/core/observation/liveViewerDiagnostics.ts"));
@@ -204,6 +206,36 @@ test("build drift is reported once with the exact loaded build", async () => {
   );
 });
 
+test("a recorded viewer reloads only when its failed lazy module belongs to a stale build", async () => {
+  const reloads = [];
+  const loadedUiBuildId = "/assets/index-abcdefgh.js";
+  const currentUiBuildId = "/assets/index-ijklmnop.js";
+  const fetcher = async (_url, options) => {
+    assert.equal(options.headers["X-MissionCore-UI-Build"], loadedUiBuildId);
+    return new Response(JSON.stringify({}), {
+      status: 200,
+      headers: { "X-MissionCore-UI-Build": currentUiBuildId },
+    });
+  };
+
+  assert.equal(await reloadRecordedViewerAfterStaleModuleFailure({
+    loadedUiBuildId,
+    fetcher,
+    reload: () => reloads.push("reload"),
+  }), true);
+  assert.deepEqual(reloads, ["reload"]);
+
+  assert.equal(await reloadRecordedViewerAfterStaleModuleFailure({
+    loadedUiBuildId: currentUiBuildId,
+    fetcher: async () => new Response(JSON.stringify({}), {
+      status: 200,
+      headers: { "X-MissionCore-UI-Build": currentUiBuildId },
+    }),
+    reload: () => reloads.push("unexpected"),
+  }), false);
+  assert.deepEqual(reloads, ["reload"]);
+});
+
 test("last unsubscribe fences an already queued build verification callback", () => {
   const controller = new AbortController();
   const observedSignals = [];